System and method of positron emission tomography with two axes of rotation

Abstract

System of positron emission tomography to obtain images of a subject, which comprehends: one first fixed axis of rotation; one second axis of rotation substantially parallel to the first axis, in which the second axis is rotatable around the first axis at a predefined distance; one element of support rotatably coupled to the second axis; one pair of scintillators fixed to the element of support, said pair being collinear and aligned along the same longitudinal axis; two photomultipliers, each optically coupled to one of the scintillators; in which the element of support has a free region between the pair of scintillators to receive the subject to be imaged.

The invention claimed is: 
     
       1. System of positron emission tomography for obtaining images of a subject, comprising:
 a first fixed axis of rotation; 
 a second axis of rotation substantially parallel to the first fixed axis of rotation, wherein the second axis of rotation is rotatable about the first fixed axis of rotation at a predefined distance; 
 an element of support rotatably coupled to the second axis of rotation; 
 a pair of scintillators fixed to the element of support, said pair of scintillators and said element of support being collinear and aligned along a same longitudinal axis; 
 two photomultipliers, each one optically coupled to one scintillator of the pair of scintillators; 
 wherein the element of support has a free region between the pair of scintillators for receiving the subject to be imaged. 
 
     
     
       2. System according to  claim 1  wherein the element of support is a plate. 
     
     
       3. System according to  claim 1  wherein the first fixed axis of rotation is fixed to the same referential of the subject to be imaged. 
     
     
       4. System according to  claim 1  wherein the second axis of rotation is parallel to a frontal face of one of the pair of scintillators. 
     
     
       5. System according to  claim 1  wherein the second axis of rotation is coincident with a frontal face of one scintillator of the pair of scintillators. 
     
     
       6. System according to  claim 1  comprising one or more additional pairs of scintillators fixed to the element of support, each additional pair of scintillators being collinear and aligned along a same longitudinal axis, and respective photomultipliers, each one optically coupled to one of the additional pair of scintillators. 
     
     
       7. System according to  claim 1  comprising an electronic system for readout of signals from the photomultipliers comprising individual amplifying circuits and coincidence detection circuits between the photomultipliers coupled to the pair of scintillators. 
     
     
       8. System according to  claim 1  wherein the first fixed axis of rotation is substantially coincident with a line bisecting the distance between each of the scintillators of the pair of scintillators. 
     
     
       9. System according to  claim 1  wherein the predefined distance at which the second axis of rotation is rotatable about the first fixed axis of rotation is substantially equal to half of the distance between each of the scintillators of the pair of scintillators. 
     
     
       10. System according to  claim 1  wherein the pair or pairs of scintillators, photomultipliers and a respective supply unit and electronic readout system are placed and integrated in the same support plate. 
     
     
       11. System according to  claim 1  wherein the scintillators are scintillator crystals. 
     
     
       12. Method of acquisition of images of a subject by positron emission tomography using a system according to  claim 1 , comprising acquiring lines of response, in the form of coincidences of signal between the photomultipliers, in different angular positions of each one of the first fixed axis of rotation and the second axis of rotation. 
     
     
       13. Method according to  claim 12 , comprising alternately rotating the first fixed axis of rotation and the second axis of rotation, wherein the first fixed axis of rotation scans an angle of up to 360 degrees and, for each position of the first fixed axis of rotation the second axis of rotation scans an angle of up to 180 degrees, to define a field of view of up to 180 degrees as scanned by the second axis of rotation, said field of view being rotatable by 360 degrees about the first axis of rotation. 
     
     
       14. Method according to  claim 12 , comprising repeating the alternate rotation of the first fixed axis of rotation and the second axis of rotation for a predefined number of times. 
     
     
       15. Method according to  claim 12 , comprising counting the number of lines of response in each pair of scintillators, for each position of the first fixed axis of rotation and the second axis of rotation. 
     
     
       16. Method according to  claim 15  wherein the coincidences are between opposing scintillators of the same pair or of different pairs of scintillators. 
     
     
       17. Method according to  claim 12 , comprising communicating the angular position of each one of the first fixed axis of rotation and second axis of rotation and the number of lines of response for each position of the first fixed axis of rotation and the second axis of rotation, from a controller unit to a computer, where the image of the subject is reconstructed, preferentially in real time during said acquisition. 
     
     
       18. Method according to  claim 12 , wherein the system counts the number of lines of response during a predefined stoppage time for each position of the first fixed axis of rotation and the second axis of rotation. 
     
     
       19. Method according to  claim 12 , wherein the system counts the number of lines of response during a continuous movement of the first fixed axis of rotation and the second axis of rotation. 
     
     
       20. Non-transitory data storage medium comprising program instructions for implementing a system of acquisition of a subject's images by positron emission tomography, the program instructions including instructions executable to carry out the method of  claim 12 .